Estimation of soil water erosion using RUSLE, GIS, and remote sensing in Obibia River watershed, Anambra, Nigeria

Abstract

The urban watershed of Obibia River is rapidly being degraded owing to pressures from increasing population and associated land-use changes. Erosion, an aspect of land degradation, has often been assumed to be costly and catastrophic due to the inability to accurately detect its occurrence at the early stages to initiate conservation measures. This study aims to apply revised universal soil loss equation (RUSLE), remote sensing, and geographic information system (GIS) to accurately detect incipient soil erosion hazards in Obibia River watershed. The multi-source data for RUSLE was based on erosion factors of rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), and the vegetation (C) combined within a GIS environment. The erosion hazard map indicated erosion categories were: very low (55.1% <20 t ha-1 yr-1), low (31.3% 21-82 t ha-1 yr-1), medium (9.4% 82-243 t ha-1 yr-1), high (3% 234-543 t ha-1 yr-1); and extreme (1.2% >543 t ha-1 yr-1). Most extreme forms of erosion occurred in undulating landscapes near river bodies. The entire erosion categories require urgent management considerations except for the low categorization. The data can be relied upon for hydro-soil erosion identification, management, and control.